diff --git a/src/compiler/crystal/tools/doc/generator.cr b/src/compiler/crystal/tools/doc/generator.cr
index 4c5988cccae5..e956ac8c3012 100644
--- a/src/compiler/crystal/tools/doc/generator.cr
+++ b/src/compiler/crystal/tools/doc/generator.cr
@@ -134,7 +134,7 @@ class Crystal::Doc::Generator
   end
 
   def must_include?(type : Crystal::Type)
-    return false if type.private?
+    return false if type.private? && !showdoc?(type)
     return false if nodoc? type
     return true if crystal_builtin?(type)
 
@@ -215,6 +215,25 @@ class Crystal::Doc::Generator
     nodoc? obj.doc.try &.strip
   end
 
+  def showdoc?(str : String?) : Bool
+    return false if !str || !@program.wants_doc?
+    str.starts_with?(":showdoc:")
+  end
+
+  def showdoc?(obj : Crystal::Type)
+    return false if !@program.wants_doc?
+
+    if showdoc?(obj.doc.try &.strip)
+      return true
+    end
+
+    obj.each_namespace do |ns|
+      return true if showdoc?(ns.doc.try &.strip)
+    end
+
+    false
+  end
+
   def crystal_builtin?(type)
     return false unless project_info.crystal_stdlib?
     # TODO: Enabling this allows links to `NoReturn` to work, but has two `NoReturn`s show up in the sidebar
@@ -267,7 +286,7 @@ class Crystal::Doc::Generator
     types = [] of Constant
 
     parent.type.types?.try &.each_value do |type|
-      if type.is_a?(Const) && must_include?(type) && !type.private?
+      if type.is_a?(Const) && must_include?(type) && (!type.private? || showdoc?(type))
         types << Constant.new(self, parent, type)
       end
     end
@@ -296,7 +315,7 @@ class Crystal::Doc::Generator
   end
 
   def doc(obj : Type | Method | Macro | Constant)
-    doc = obj.doc
+    doc = obj.doc.try &.strip.lchop(":showdoc:")
 
     return if !doc && !has_doc_annotations?(obj)
 
diff --git a/src/compiler/crystal/tools/doc/html/_method_detail.html b/src/compiler/crystal/tools/doc/html/_method_detail.html
index 3fc3d5cd760b..1520d2a4a610 100644
--- a/src/compiler/crystal/tools/doc/html/_method_detail.html
+++ b/src/compiler/crystal/tools/doc/html/_method_detail.html
@@ -6,7 +6,7 @@ <h2>
   <% methods.each do |method| %>
     <div class="entry-detail" id="<%= method.html_id %>">
       <div class="signature">
-        <%= method.abstract? ? "abstract " : "" %>
+        <%= method.abstract? ? "abstract " : "" %><%= method.visibility %>
         <%= method.kind %><strong><%= method.name %></strong><%= method.args_to_html %>
 
         <a class="method-permalink" href="<%= method.anchor %>">#</a>
diff --git a/src/compiler/crystal/tools/doc/html/type.html b/src/compiler/crystal/tools/doc/html/type.html
index 10c7e51fedd3..fb1dbbe94f13 100644
--- a/src/compiler/crystal/tools/doc/html/type.html
+++ b/src/compiler/crystal/tools/doc/html/type.html
@@ -19,7 +19,9 @@ <h1 class="type-name">
 <% if type.program? %>
   <%= type.full_name.gsub("::", "::<wbr>") %>
 <% else %>
-  <span class="kind"><%= type.abstract? ? "abstract " : ""%><%= type.kind %></span> <%= type.full_name.gsub("::", "::<wbr>") %>
+  <span class="kind">
+    <%= type.abstract? ? "abstract " : ""%><%= type.visibility %><%= type.kind %>
+  </span> <%= type.full_name.gsub("::", "::<wbr>") %>
 <% end %>
 </h1>
 
diff --git a/src/compiler/crystal/tools/doc/macro.cr b/src/compiler/crystal/tools/doc/macro.cr
index 49b9c30795bc..629eccc2e225 100644
--- a/src/compiler/crystal/tools/doc/macro.cr
+++ b/src/compiler/crystal/tools/doc/macro.cr
@@ -54,6 +54,10 @@ class Crystal::Doc::Macro
     false
   end
 
+  def visibility
+    @type.visibility
+  end
+
   def kind
     "macro "
   end
diff --git a/src/compiler/crystal/tools/doc/method.cr b/src/compiler/crystal/tools/doc/method.cr
index 069deb48ee61..7f71a9c42440 100644
--- a/src/compiler/crystal/tools/doc/method.cr
+++ b/src/compiler/crystal/tools/doc/method.cr
@@ -43,7 +43,7 @@ class Crystal::Doc::Method
   # This docs not include the "Description copied from ..." banner
   # in case it's needed.
   def doc
-    doc_info.doc
+    doc_info.doc.try &.strip.lchop(":showdoc:")
   end
 
   # Returns the type this method's docs are copied from, but
@@ -135,6 +135,16 @@ class Crystal::Doc::Method
     end
   end
 
+  def visibility
+    case @def.visibility
+    in .public?
+    in .protected?
+      "protected "
+    in .private?
+      "private "
+    end
+  end
+
   def constructor?
     return false unless @class_method
     return true if name == "new"
@@ -323,6 +333,7 @@ class Crystal::Doc::Method
       builder.field "doc", doc unless doc.nil?
       builder.field "summary", formatted_summary unless formatted_summary.nil?
       builder.field "abstract", abstract?
+      builder.field "visibility", visibility if visibility
       builder.field "args", args unless args.empty?
       builder.field "args_string", args_to_s unless args.empty?
       builder.field "args_html", args_to_html unless args.empty?
diff --git a/src/compiler/crystal/tools/doc/type.cr b/src/compiler/crystal/tools/doc/type.cr
index 624c8f017fe7..69857cbd3306 100644
--- a/src/compiler/crystal/tools/doc/type.cr
+++ b/src/compiler/crystal/tools/doc/type.cr
@@ -81,6 +81,10 @@ class Crystal::Doc::Type
     @type.abstract?
   end
 
+  def visibility
+    @type.private? ? "private " : nil
+  end
+
   def parents_of?(type)
     return false unless type
 
@@ -181,7 +185,7 @@ class Crystal::Doc::Type
         defs = [] of Method
         @type.defs.try &.each do |def_name, defs_with_metadata|
           defs_with_metadata.each do |def_with_metadata|
-            next unless def_with_metadata.def.visibility.public?
+            next if !def_with_metadata.def.visibility.public? && !showdoc?(def_with_metadata.def)
             next unless @generator.must_include? def_with_metadata.def
 
             defs << method(def_with_metadata.def, false)
@@ -192,6 +196,10 @@ class Crystal::Doc::Type
     end
   end
 
+  private def showdoc?(adef)
+    @generator.showdoc?(adef.doc.try &.strip) || @generator.showdoc?(@type)
+  end
+
   private def sort_order(item)
     # Sort operators first, then alphanumeric (case-insensitive).
     {item.name[0].alphanumeric? ? 1 : 0, item.name.downcase}
@@ -205,7 +213,7 @@ class Crystal::Doc::Type
       @type.metaclass.defs.try &.each_value do |defs_with_metadata|
         defs_with_metadata.each do |def_with_metadata|
           a_def = def_with_metadata.def
-          next unless a_def.visibility.public?
+          next if !def_with_metadata.def.visibility.public? && !showdoc?(def_with_metadata.def)
 
           body = a_def.body
 
@@ -236,7 +244,9 @@ class Crystal::Doc::Type
       macros = [] of Macro
       @type.metaclass.macros.try &.each_value do |the_macros|
         the_macros.each do |a_macro|
-          if a_macro.visibility.public? && @generator.must_include? a_macro
+          next if !a_macro.visibility.public? && !showdoc?(a_macro)
+
+          if @generator.must_include? a_macro
             macros << self.macro(a_macro)
           end
         end